In Microsoft Outlook, you experience one of the following issues when you try to configure free/busy information or when you try to delegate information: 

  • When you accept a meeting request or when you add a delegate to your mailbox, you receive the following error message:

    Unable to save free/busy information

  • When you use the outlook.exe /cleanfreebusy command-line switch to start Outlook, you receive the following error message:

    Unable to clean your local free/busy information.

  • When you try to add a delegate, you receive one of the following error messages:

    The Delegates settings were not saved correctly. Unable to activate free/busy information.

    The Delegates settings were not saved correctly. Unable to activate send-on-behalf-of list. You do not have sufficient permission to perform this operation on this object.

  • When you try to open a shared calendar item, you receive the following error message:

    Can't open this item. Unable to open the free/busy information

    Additionally, the following event is logged in the Application log on the Outlook client computer:

    Event Type: Warning
    Event Source: Outlook
    Event Category: None
    Event ID: 25
    Date: date
    Time: time
    User: N/A
    Computer: Computer_name
    Unable to save free/busy information. Unable to open the free/busy information.

  • When a delegate tries to create an item in the shared calendar or in the manager calendar, the delegate receives the following error message:

    Unable to open free/busy information


These issues occur because a mailbox property does not correctly reference a hidden message in the mailbox. The hidden message contains information that is related to any of the following features:

  • free/busy publishing

  • delegate

  • direct booking


To resolve this issue, use one of the following methods to force the regeneration of hidden free/busy information in the mailbox.

The steps in this section must be applied on the mailbox of the user who owns the Calendar folder. This is the mailbox on which you try to create the calendar items, use the /cleanfreebusy switch, or configure the delegate settings. 

Note: The /cleanfreebusy switch is not available in Outlook 2016 and later versions. Instead, you can use the /cleanroamedprefs switch.

After you follow these steps, you may have to reconfigure settings that are related to the delegates and direct booking features.

Method 1: Use PowerShell cmdlet

You must have the administrator permission to run the PowerShell cmdlets to delete the free/busy configuration on the mailbox, and then add or recreate any necessary delegate permissions:

  1. Run the following cmdlet to export the current Calendar folder permissions, which may be needed to recreate any delegate permission settings:

    Get-MailboxFolderPermission -Identity <alias>:\Calendar

  2. Run the following PowerShell cmdlet against the target mailbox:

    Remove-MailboxFolderPermission -Identity <alias>:\Calendar -ResetDelegateUserCollection

    Note See Remove-MailboxFolderPermission for more details on the ResetDelegateUserCollection parameter.

  3. Run the following cmdlet one or more times, as needed, to add or recreate any necessary delegate permissions:

    Add-MailboxFolderPermission -Identity <alias>:\Calendar -User <delegate alias> -SharingPermissionFlag Delegate

Method 2: Use MFCMAPI tool

Follow these steps:

  1. Exit Outlook.

  2. Make sure a profile (preferably configured for Online mode) exists for the mailbox.

    Note If no profile exists for the mailbox, use the Mail item in Control Panel to create it.

  3. Download the MFCMAPI tool.

  4. Start the MFCMapi.exe program that you downloaded, and then select OK.

  5. If the profile is configured for Cached mode, use the following steps to temporarily force Online mode within MFCMAPI:

    1. On the Tools menu, select Options.

    2. Enable the following two options, and then select OK.

      • Use the MDB_ONLINE flag when calling OpenMsgStore

      • Use the MAPI_NO_CACHE flag when calling OpenEntry

  6. On the Session menu, select Logon.

  7. In the Profile Name list, select the profile for the mailbox, and then select OK.

  8. Double-click the appropriate Microsoft Exchange Message Store.

  9. In the navigation pane, select Root Container.

  10. In the details pane, right-click PR_FREEBUSY_ENTRYIDS, select Delete Property, and then select OK.

  11. In the navigation pane, expand Root Container, expand Top of Information Store, and then select Inbox

    NoteTop of Information Store could be localized to another language depending on mailbox regional settings.

  12. In the details pane, right-click PR_FREEBUSY_ENTRYIDS, select Delete Property, and then select OK.

  13. Delete the LocalFreeBusy message by using the following steps:

    1. In the navigation pane, expand Root Container.

    2. Double-click Freebusy Data.

    3. In the upper pane, find the item with the Subject of LocalFreebusy. Right-click it, and then select Delete message.

    4. For Deletion style, select Permanent delete passing DELETE_HARD_DELETE (unrecoverable), and then select OK.

  14. Close all the MFCMAPI windows.

Reconfigure delegates permissions and direct booking

If you have any custom settings that are related to the delegates feature, or the direct booking feature, follow the appropriate steps.

For the delegates feature

  1. Start Outlook.

  2. On the File tab, select Account Settings, and then select Delegate Access.

  3. Select the delegate that you want to reconfigure, and then select Permissions.

  4. Click to select the options that you want in the Delegate Permissions dialog box, and then select OK.

  5. Repeat step 3 and step 4 for all delegates.

  6. Select OK.

  7. On the File tab, select Exit.

For the direct booking feature
  1. Start Outlook.

  2. On the File tab, select Options, and then select Calendar.

  3. In Outlook 2016 or 2013, select Auto Accept/Decline, or in Outlook 2010, select Resource Scheduling.

  4. Click to select the check boxes that you want.

  5. Select OK two times.

  6. On the File menu, select Exit.

Need more help?

Expand your skills
Explore Training
Get new features first
Join Microsoft Insiders

Was this information helpful?

What affected your experience?

Thank you for your feedback!